The line began at the bookshop door and stretched as far as the eye could see. Two young men, obtrusive in high-vis jackets, surveyed it and marvelled. "It goes all the way to Trafalgar Square," one told the other. A third of a mile. "And there's more coming," said a voice from the queue; a stocky guy in a brown suede jacket.

We all have our enthusiasms. Some cut across ages and cultures and communities. Others are specific. This is one of those: a phenomenon can engender wild enthusiasm without registering with the rest of us. We might live cheek by jowl; but there's a limit to what we know.

The author is Bishop Edir Macedo. I'd never heard of him either. But he's a hugely controversial preacher, and huge in South America and parts of Africa and now, it seems, in the UK, by dint of having founded the Universal Church of the Kingdom of God in Brazil. The evangelical pentecostal church, with its UK base in north London, has 27 branches here; 15 in London, others in places such as Birmingham, Cardiff and Gravesend.

Macedo's book, Nothing to Lose, launched in his native Brazil last year, has already sold a million copies. This is the UK launch, and it's a must-attend for around 3,000 people – predominantly of African or West Indian origin, mostly middle-aged, mostly women. More than 15,000 copies will be sold on this day. Good business at £12 each.

Wandering down the line, past a jolly group of women who wave their union flags, I chat with Dan Bosisa Edidjimo, a 24-year-old student originally from Congo. He's buying five copies but he knows a woman who's buying 150. "It's not just the book," he says."It's what's behind the book. I'll send you a copy."

Maria Carvalho, rosy-cheeked, from north London and Portugal, has waited four hours and her reward is the very front of the queue.

Macedo isn't coming; his representatives will deputise. She doesn't care. Steve Orchard, the bookshop manager, has seen euphoria. Will Self drew a crowd, as did David Attenborough. But right now, fighting for trade and menaced by Amazon, heady days are hoped for rather than expected. The tales of a Brazilian pastor: a moneyspinner in the heart of central London. Who knew?